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C. J. BEAVER AND E. A. CLAREMONT.

MANUFACTURE OF ELECTRIC CABLES.

APPLICATION FILED NOV. 21. 1918 1,305,247. Patented June 3, 1919.

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UNITED STATES PATENT OFFICE.

CHARLES JAMES BEAVER, 0F HALE, AND ERNEST ALEXANDER CLABEMDNT, 01 E163LEGH, ENGLAND.

MANUFACTURE OF ELECTRIC "A Specification of Letters Patent.

Patented June 3, 1919.

Application filed November 27, 1918. Serial No. 264,377.

To all whom it may concern:

Be it known that we, CHARLES JAMES BEAVER, of Hale, Cheshire, England,and ERNEST ALEXANDER CLAREMONT, of High Legh, Cheshire, England,subjects of the King of Great Britain and Ireland, have invented certainnew and useful Im rovements in the Manufacture of Electric. ables, ofwhich the following is a specification.

This invention relates to the manufacture of electric cables andcomprises a modification or improvement of .our invention described inthe s ecification of United States Letters Patent 0. 1,298,644.

In the said specification we described a twin core cable composed of twoconductors separated by a strip of rubber or other suitable insulatingmaterial of sufficient thickness to insulate them with an outer coveringconsisting of two strips of rubber or other suitable insulatingmaterial, the edges of which were joined and rendered autogenous bypressure.

According to the present invention the two conductors are twisted orspiraled around one another and the strip of insulating materialseparating the conductors is made elastic and compressible so as toenable the twisted conductors to assume a longer lay with acorrespondingly smaller internal diameter of the spirals; therefore, wemake the strip of insulating material separating the two conductors ofrubber in an elastic and compressible condition or other suitablematerial yielding the said qualities, and further, we may make saidinsulating material in the form of a hollow tube in order to increaseits compressibility.

In the accompanying drawings we illustrate examples of our inventionFigure 1 being a cross section through the cable in which the conductorsare separated by a solid or spongy elastic and compressible material,and Fig. 2 a similar cross section showing a hollow separating strip. Inboth figures, like letters indicate like parts.

a and a are the conductors, b is the separating strip of insulatingmaterial of such thickness and such degree of elasticity andcompressibility as to allow the desired dearound one another gree ofextensibility of the cable as a whole.

0 is the overall insulation completely inclosing the conductors a and a.As described in our aforesaid Patent No. 1,298,644 the overall strips ofinsulation and the separating strip b are united by pressureand thecable is subsequently vulcanized. The material of which the overallinsulation 0 is composed may be less compressible than the strip 1) formechanical reasons, but must be sufiiciently elastic to extend to therequired degree. The thickness of the separating strip b is preferablygreat as compared with the minimum. thickness of the overall insulation0.

In Fig. 2, the separating strip 1) is constructed with a centralcontinuous air cavity lrunning throughout its length as shown at What weclaim as our invention and desire to secure by Letters Patent of theUnited States is 1. A circular or approximately circular electric cableconsisting of two conductors, insulation between such conductorscomposed of flexible insulating material in an elastic and compressiblecondition in the form of a strip not thicker than necessary to securethe required elasticity and compressibility and efficient insulation,and an exterior insulation composed of elastic material in the form oftwo strips respectively folded half around the cable and the edges ofthe three strips of rubber or other material caused to adhere and becomeautogenous by pressure with theconductors spiralcd substantially asdescribed.

2. A cable as claimed in claim 1, having the strip of insulatingmaterial separating the conductors formed with a continuous centralhollow or air cavity.

In witness whereof we have signed this specification in the presence oftwo witnesses.

Witnesses:

C. A. NEALE, J. Pnnmrs.

